The invention is a changeable signboard. The conventional changeable signboards are as shown in FIG. 4, composed of a large number of fragmental small changeable faces which are fixed on a respective worm gear or barbell gear 2 that is counter-revolving against the screw shaft of the long main shaft, and the faces are to be changed concurrently. When the signboards are installed outdoor or on the rooftop, dust or other foreign material may deposit on or between the worm gears and screw, causing the malfunction of one of them. For example, if teeth of a gear wear out or fail to revolve against the screw, the face of the gear does not turn around causing an undiscernible pattern of advertisement or the whole rig may stop functioning, thus defeating the purpose of the advertisement.
The conventional signboard requires a high power motor to drive the main shaft which consumes a great deal of electricity and demands a vast space to install the motor and its controlling accessories, thus resulting in high cost of installation. Moreover, extended use may cause a deviation to the teeth of the gear by wearing. The deviated turning angle of the gear may result in a different advertisement than the one first intended, and in extended repair cost and trouble. Also, the limited length of the screw gear may enable one to display only the limited pattern of an advertisement.
The present invention compensates the drawbacks of the conventional signboards in the following ways:
1. A stepping motor is installed to each turning shaft of a fragmental face.
2. Each motor is programmed to obtain desired patterns of advertisements.
3. Each fragmental face can turn clockwise or counterclockwise respectively, or can turn to a desired angle and stop.
4. The sign is changeable in part or in whole as desired.
5. The advertisement rig is electronized to obtain a better result of an advertisement and compactness of the system.
6. A parabolic screen may be created if wanted. The invention is not limited to a horizontal or vertical screen which is the case of a conventional signboard.
7. The screen can be widened to be as large as one wishes.